The aim of this experiment is to study the effect of solid solution strengtheners on deformation mechanisms in Titanium alloys with particular emphasis on studying twinning. Aluminium is the main alpha phase stabilising and solid solution strengthening element in commercial Ti alloys for lightweight applications. In order to develop new high strength Ti alloys in the future, a much improved understanding of the effect of alloying elements on deformation mechanisms is highly desirable. Previous measurements on ENGIN-X demonstrated a non-linear decrease in twin evolution with increasing Al content but suggested combined effects of SRO and SFE on nucleation stresses. The proposed in-situ loading experiments on ENGIN-X aim to understand the role of Aluminium on the nucleation of nucleation criteria of twinning. The results will be interpreted using crystal plasticity modelling.